The invention relates generally to x-ray detectors and, more particularly, to the material and construction of structural components of portable digital x-ray detectors.
Imaging systems are utilized for various applications in both medical and non-medical fields. For example, medical imaging systems include general radiological, mammography, x-ray C-arm, tomosynthesis, and computed tomography (CT) imaging systems. These various imaging systems, with their different respective topologies, are used to create images or views of a patient for clinical diagnosis based on the attenuation of radiation (e.g., x-rays) passing through the patient. Alternatively, imaging systems may also be utilized in non-medical applications, such as in industrial quality control or in security screening of passenger luggage, packages, and/or cargo. In such applications, acquired data and/or generated images representing volumes or parts of volumes (e.g., slices) may be used to detect objects, shapes or irregularities which are otherwise hidden from visual inspection and which are of interest to the screener.
Typically, x-ray imaging systems, both medical and non-medical, utilize an x-ray tube to generate the x-rays used in the imaging process. The generated x-rays pass through the imaged object where they are absorbed or attenuated based on the internal structure and composition of the object, creating a matrix or profile of x-ray beams of different strengths. The attenuated x-rays impinge upon an x-ray detector designed to convert the incident x-ray energy into a form usable in image reconstruction. Thus the x-ray profile of attenuated x-rays is sensed and recorded by the x-ray detector. Typically, x-ray detectors are based on film-screen, computed radiography (CR) or digital radiography (DR) technologies. In film-screen detectors, the x-ray image is generated through the chemical development of the photosensitive film after x-ray exposure. In CR detectors, a storage phosphor imaging plate captures the radiographic image. The plate is then transferred to a laser image reader to “release” the latent image from the phosphor and create a digitized image. In DR detectors, a scintillating layer absorbs x-rays and subsequently generates light, which is then detected by a two-dimensional (2D) flat panel array of silicon photo-detectors. Absorption of light in the silicon photo-detectors creates electrical charge. A control system electronically reads out the electrical charge stored in the x-ray detector and uses it to generate a viewable digitized x-ray image.
Digital x-ray detectors typically fabricate the 2D flat panel array of silicon photo-detectors on a glass substrate (imaging panel). Since the imaging panel is fragile, it must therefore be mechanically supported, by some type of panel supports, during use. The panel support also provides stiffness to the overall detector package. Additionally, an external housing or enclosure may be provided to protect the imaging panel. A portion of this external enclosure is generally comprised of a material with low x-ray attenuation characteristics to allow incident x-ray radiation to readily reach the imaging panel.
Typically, the panel supports and the external protective enclosures are composed of heavy machined metal, such as magnesium, so as to provide a high degree of mechanical protection to the flat panel substrate and associated read-out electronic components located within the external housing. Further, the currently available x-ray detectors are based on multi-piece metallic external enclosure assemblies having many weak mechanical seams and screw fasteners both of which are prone to mechanical failure if the detector is dropped or impacted with a rigid object.
Thus, the conventional construction of x-ray detectors results in a relatively heavy and thick x-ray detector that is prone to mechanical failure upon dropping the detector onto a hard surface (i.e. case can dent or break apart). This is particularly problematic for portable x-ray detector designs that should be ideally lightweight while withstanding multiple accidental impact loads. However, the relatively thick and heavy panel support and external enclosure is required to protect the sensitive and fragile imaging components and the readout electronics as these portable detectors are typically used in environments where they can be dropped, impacted with a rigid object, or subjected to a patient load, e.g., placed directly beneath a patient being imaged. For example, the rigid external enclosure prevents the readout electronics from being pressed into the imaging components when subjected to heavy load.
It is therefore desirable to provide an x-ray detector that is lightweight yet mechanically stiff and rugged to withstand heavy impact or support patient loads placed on the detector surface. It is also desirable to provide a stiff support plate onto which the imaging panel is attached so as to protect internal elements of the detector from damage due to heavy impact or patient loads. Additionally, it is desirable to provide a stiff and rugged external enclosure while minimizing or eliminating the weak mechanical attachment points and fasteners required by a multi-piece external enclosure assembly.